## Facts

- Two related PTO interferences concerned (1) a genus of cholesterol-inhibiting mevalonolactone compounds and (2) a therapeutic method of inhibiting cholesterol biosynthesis by administering a compound within that genus.
- Fujikawa (senior party) performed inventive activity outside the United States and, for priority purposes, could rely only on an effective U.S. filing date of August 20, 1987.
- Wattanasin (junior party), working with Sandoz, pursued research beginning in the early 1980s, including synthesis of compounds within the interference count and testing for cholesterol-inhibiting activity.
- The Board found Wattanasin established actual reduction to practice through successful in vivo testing demonstrating recognized utility prior to Fujikawa’s effective filing date.
- After reduction to practice, Sandoz filed a patent application in March 1989 following internal evaluation and development activity; the Board found no suppression or concealment despite an approximately 15–17 month gap.
- Fujikawa moved to add an additional, narrower subgenus count to the interference; the Board denied the motion, concluding Wattanasin’s disclosure lacked written description support because it did not identify the proposed subgenus with sufficient “blazemarks.”
- Fujikawa appealed the Board’s priority determinations and denial of the subgenus-count motion to the Federal Circuit.

## Issues

1. Whether substantial evidence supported the Board’s award of priority to Wattanasin under 35 U.S.C. § 102(g), including the Board’s reduction-to-practice finding.
2. Whether the 15–17 month period between Wattanasin’s reduction to practice and patent filing constituted suppression or concealment under § 102(g).
3. Whether the Board properly denied Fujikawa’s motion to add a subgenus count for lack of adequate written description support in Wattanasin’s disclosure.

## Decision

- The Federal Circuit affirmed the Board’s decisions in full.
- The court upheld the Board’s finding that Wattanasin proved priority over Fujikawa under § 102(g), including the Board’s reduction-to-practice determination.
- The court upheld the Board’s finding that Wattanasin did not suppress or conceal the invention; the filing delay was not unreasonable on this record.
- The court affirmed denial of the motion to add a subgenus count because Wattanasin’s disclosure lacked written description support for the proposed subgenus, including absence of sufficient “blazemarks.”

## Legal Principles

- In an interference under 35 U.S.C. § 102(g), a party may establish priority by proving conception and diligence through reduction to practice, and by showing no suppression or concealment between reduction to practice and filing.
- Where a party’s inventive activity occurred abroad, priority in the interference may be limited to the party’s effective U.S. filing date.
- Suppression or concealment is assessed in context; a delay between reduction to practice and filing does not, by itself, establish concealment where the record shows continued activity consistent with development and patenting rather than abandonment or intentional withholding.
- Written description for a later-asserted subgenus within a broadly disclosed genus requires more than undifferentiated inclusion within the genus; the disclosure must contain “blazemarks” or other guidance directing a skilled artisan to the claimed subgenus.

## Conclusion

The Federal Circuit sustained the PTO’s award of priority to Wattanasin because substantial evidence supported conception, diligence, and reduction to practice before Fujikawa’s effective U.S. filing date and because the post-reduction delay did not amount to suppression or concealment; it also affirmed denial of a proposed subgenus interference count due to inadequate written description support without “blazemarks.”


Fujikawa v. Wattanasin, 93 F.3d 1559 (Fed. Cir. 1996)